An existing multidepartmental, interdisciplinary program of research projects and core facilities focusing on gonadotropins in reproductive biology has been brought together as a Specialized Population Research Center. The Center involves the efforts of 11 faculty members associated with 7 departments in the University: Anatomy, Internal Medicine, Obstetrics and Gynecology, Oral Biology, Pathology, Pediatrics and Physiology. The approaches involved range from cellular and molecular to physiological and clinical, with extensive integration of the various levels. Animal models include rats, rabbits, sheep, monkeys and human beings. Major research emphasis is on the following problem areas: role of gonadotropins in regulation of ovarian cyclicity; localization, regulation, function and action of gonadotropin releasing hormone; estrogen action in corpora lutea; and molecular and cellular mechanisms and consequences of gonadotropin action in the ovary, inclucing the regulation of follicular development.